'The conduct of this bank is anything but ethical.'

A joint Fairfax Media and Four Corners investigation has exposed claims from CommInsure's former chief medical officer Dr Benjamin Koh of a culture where doctors are pressured to alter or delete medical records and opinions to allow the Commonwealth Bank subsidiary to avoid paying claims.

Nearly three million Australians are covered by CommInsure through its deals to offer life and total permanent disability policies to members of nine industry and two public sector funds .

In January, CommInsure announced it had won tender to replace MetLife as the insurance provider for Prime Super, whose 125,000 members are largely agricultural workers. That contract, which is due to commence on May 1, is now under threat.

Prime Super chief executive Lachlan Baird said he was "very concerned" by the allegations raised and had sought more information from CommInsure.

"We are spending a lot of time with CommInsure working through these issues this week. If we are not satisfied with the responses we receive from then we will need to consider our options for the future," Mr Baird said.

"Where our experience does not match with our expectations for any insurer, we will look to terminate the arrangement and go to market again."

The Fairfax Media and Four Corners investigation also raised concerns about the use of outdated definitions by CommInsure to avoid paying out on trauma coverage for heart attack sufferers.

Chant West head of research Ian Fryer said it was important for members of the public concerned by the allegations to understand that the life and total permanent disability policies they have through their super fund can not by law include trauma coverage, so super members are not affected by this issue.

Mr Fryer said super fund members should not make any rash changes to their insurance arrangements that might disadvantage them in the long term.

Other allegations of unfair practices include claims made by former CommInsure employee and Helen Polydoropoulos who had two policies, one direct and one through her membership of industry fund Kinetic Super.

CommInsure's contract with Kinetic for its 298,000 members is up for review this year.

"In selecting an insurance provider, we will consider a number of factors including the adequacy and affordability of the cover, the insurer's track record with payment of claims and the quality of service provided to our members," Ms Thomas said.

Evan Pashalis, a policyholder through his super fund CareSuper, has claimed that CommInsure unfairly refused to release his death benefit early after he was diagnosed with terminal cancer.

CareSuper chief executive Julie Lander declined to comment on Mr Pashalis' individual case but said the fund was "deeply concerned" by the allegations and had been previously unaware of allegations raised by Dr Koh.

The revelations will cast a shadow over a periodic review of the fund's contract with CommInsure currently underway and due to be finalised by July.

"Our policy has always been to partner with organisations who share our values and our commitment to fulfilling our members' needs and representing our members' best interests," Ms Lander said.

The Commonwealth Bank Group declined to comment.

NGS Super is another client with its contract up for review this year.

"If any of our business partners do not meet these standards, this may trigger a new partner tender," NGS Super chairman Anthony Rodwell-Ball said.

Tasplan chief executive Naomi Edwards said her board would decide whether or not to commence a review once it received more information from CommInsure.

"Our partners must understand our member first philosophy," she said.

HESTA chief executive Debby Blakey issued a statement promising to support any of that fund's members who wished to seek a review of a past claim denied by CommInsure.

Vision Super also issued a statement inviting any of its members who believed they had been treated unfairly by CommInsure to contact them for a review.

Other non-profit funds that use CommInsure for their life and permanent disability coverage are QIEC Super, Club Super, RBF Tasmania, TWU Super, and AustSafe.